Free floating pressure roller means and retracting mechanism for film drive

ABSTRACT

Slippage of a wide film engaged by a driving capstan is prevented by resiliently urging a pair of rollers mounted in a free floating yoke structure against the drive capstan. The yoke structure is guided by a frame means which also includes cam means for effecting the urging of the yoke structure. A lever element terminating in a hook is arranged to engage a bearing on the free end of the capstan to stabilize the same when the pressure rollers are in engagement with the capstan.

United States Patent Renold [4 June 13, 1972 [54] FREE FLOATING PRESSUREROLLER MEANS AND RETRACTING MECHANISM FOR FILM DRIVE [72] Inventor:Walter Renold, 7044 Mary Ellen Avenue, Hollywood, Calif. 91605 [22]Filed: March 4, 1971 211 Appl. No.: 120,965

52] use] ..226/l76,226/l87,226/l83 51 me]. ..G11b15/29 5s FieldofSearch..226/l83,187,l76,177

[ 56] References Cited UNITED STATES PATENTS 2,858,130 10/1958 Baur etal. L83

Primary Examiner-Allen N. Knowles Attorney-Pastoriza & Kelly [5 7]ABSTRACT Slippage of a wide film engaged by a driving capstan isprevented by resiliently urging a pair of rollers mounted in a freefloating yoke structure against the drive capstan. The yoke structure isguided by a frame means which also includes cam means for efi'ecting theurging of the yoke structure A lever element terminating in a hook isarranged to engage a bearing on the free end of the capstan to stabilizethe same when the pressure rollers are in engagement with the capstan.

5 Claims, 1 Drawing Figure FREE FLOATING PRESSURE ROLLER MEANS AND 1RETRACTING MECHANISM FOR FILM DRIVE BACKGROUND OF THE INVENTION Incertain microfilm applications, very accurate film registration isrequired, yet the conventional methods for precision film positioningusing sprocket holes cannot be applied. This is because the film itselfis normally not provided with sprocket holes. In the particularsituation in which step-and-repeat cameras are used, it is desirable tomove the same strip of wide film back and forth many times as rows ofsmall images are exposed. Such necessary movements accentuate thedifficulties encountered by film slippage to such an extent that theproblem is presently side-stepped in existing cameras by changing theconventional sequence of exposed images and simply moving the wholemechanism or optics back and forth laterally in a step-and-repeatfashion, the film transport only advancing the film in a forwarddirection by one step at a time at the conclusion of exposing a columnof images.

The foregoing method of film exposure seriously restricts the usefulnessof such a camera. Further, the conventional pressure roller and drivecapstan arrangements typically can only operate within a very narrowrange of applied pressure and at limited drive speeds. Too littlepressure will cause film slippage while too much pressure will cause socalled pressure marks on the photographic emulsion which have theappearance of exposed streaks.

Another problem encountered in such cameras as described above is thespace limitation within which a satisfactory roller mechanism must bemounted. Such mechanism includes arrangements for engaging anddisengaging the pressure rollers from the drive capstan in order topermit film loading.

Similar problems are present in many other mechanisms in whichunperforated film is driven.

BRIEF DESCRIPTION OF THE PRESENT INVENTION With the above in mind, thepresent inventionprovides a pressure roller means for engagement againsta drive capstan for moving film therebetween in which the film and driveroller contact is distributed over a large area thereby permittinglarger contact force with relatively small unit pressure on the film. Asa consequence, the problems associated with too little or too muchpressure are avoided and the risk of slippage is minimized.

In accord with the invention, a yoke structure rotatably mounts as leasttwo pressure rollers with their axes of rotation parallel to each other,the spacing between the rollers being less than the diameter of thedrive capstan. A frame means in turn includes guiding means permittingfree limited movement of the yoke structure in all six degrees offreedom such that the yoke structure is free floating relative to theframe means. A resilient means is connected to the yoke structure and isarranged to cooperate with an actuating means on the frame means to urgethe pressure rollers against the capstan such that the reaction forcecomponents transmitted to the supported ends of the pressure rollers inthe yoke structure are substantially equal.

In the preferred embodiment of the invention, the actuating means takesthe form of cam means including a cam shaft mounted in the frame meansfor rotation about an axis generally parallel to the axes of thepressure rollers. First and second pairs of cam members areeccentrically mounted to the shaft. The first pair of cam membersengages the resilient means on the yoke structure to cause the pressurerollers to engage the driving capstan when the cam shaft is rotated froma first position to a second position. The second pair of cam membersare arranged to engage the yoke structure itself and retract it from thedriving capstan when the cam shaft is rotated from the second positionback to the first position. By this arrangement, the film may be loadedinto position or removed .very quickly and the entire I pressure rollermechanism still is kept in a compact configuration.

An important feature of the invention resides in the provision of alever element secured to the frame means and ter minating in a hook forengaging the free end of the drive capstan when the pressure rollersengage the capstan. A stability is thus provided during the film drivingoperation.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the inventionwill be had by referring to the single accompanying drawing constitutinga perspective view of one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, there isshown a fragmentary portion of a frame means 10 which may include asupport for a driving capstan 1 I mounted on a capstan shaft 12 passingthrough a suitable bearing in the frame to a drive motor 13. A wide film14 is shown partially wrapped about the drive capstan l1.

In order to hold the film 14 against the drive capstan 1 l to insureproper driving of the film without slippage, the improved pressureroller means of the present invention is utilized. As shown, this meansincludes at least two pressure rollers 15 and 16 rotatably mountedbetween a pair of yoke anns l7 and 18 constituting part of a yokestructure 19. It will be noted that the shafts for the pressure rollers15 and 16 are parallel and the spacing between the rollers is less thanthe diameter of the driving capstan 11 so that engagement of the drivingcapstan by both rollers simultaneously is assured when the yokestructure is moved towards the capstan.

The yoke arms themselves include rearwardly extending portions 20 and 21provided with elongated slots 22 and 23. Positioned within these slotsis a pair of cam members 24 and 25 eccentrically mounted to a cam shaft26. Cam shaft 26 in turn is mounted for rotation in frame structure 10as shown at 27 for the lower end of the cam shaft and at 28 on the endof bracket 29 at the upper end of the cam shaft.

A pair of larger cam members 30 and 31 are also eccentrically mounted onthe cam shaft 26in a rnanner to engage resilient springs 32 and 33mounted on the yoke structure 19 when the cam shaft 26 is rotated from afirst to a second position.

It will be evident from the positioning of the slots 22 and 23 in theyoke structure that the entire yoke structure is free to move towardsthe capstan through engagement of the resilient springs 32 and 33. Onthe other hand, when the cam shaft 26 is rotated from its referred tosecond position back to its first position, the cam members 24 and 25will engage the far ends of the slots 22 and 23 and thus urge the entireyoke structure away from the drive capstan I l.

In accord with an important feature of this invention, the

yoke structure is free floating; that is, the frame includes suitableguide means which will permit limited motion of the yoke structure inits six degrees of freedom. As an example of such a guide means, thereis shown a slot 34 in the yoke arm 17 of the yoke structure throughwhich passes a fixed pin 35 from the frame 10. Suitable cross members 36and 37 in turn are secured to the pin on either side of the slot 34 andspaced a greater distance apart than the thickness of the yoke arm 17.It will thus be seen that slight up and down as well as lateral movementof the yoke structure is possible as well as inward and outward movementtowards and away from the capstan and yet the yoke is captured to theframe 10 through the loose guide coupling described.

The mechanism is completed by a lever element 38 having one end securedas at 39 to the upper end of the cam shaft 26. The other end of theelement 38 terminates in a hook means 40 arranged to engage about abearing 41 on the upper end of the drive capstan shaft 12 when the camshaft 26 is rotated from its first to its second position. This lever 38serves to stabilize thedrive capstan since this capstan is relativelylong and is only rotatably supported by the frame at its lower end. Along capstan is necessary to accommodate relatively wide types of filminvolved.

In the foregoing arrangement, only a very light structure is requiredfor lever 38 to give substantial support to the drive capstan, becausethe force exerted against the capstan by the pressure rollers along aline of action between the axes of shafts l2 and 26 is opposed by thelever 38 in tension along the same line of action.

OPERATION In operation, the lever element 38 is swung in the directionof the arrow 42 to its dotted line position 38'. This action notonly'releases the upper end of the drive capstan 11 but simutaneouslyretracts the yoke structure 19 and thus the rollers 15 and 16 from thedrive capstan. In this respect, and as described heretofore, the cammembers 24 and rotate with the cam shaft 26 in the slots 22 and 23 andbecause of the eccentric mounting, the desired retraction of the yokestructure takes place. It will also be appreciated that simultaneouslywith this same motion, the cam members and 31 are rotated thus relievingpressure against the resilient springs 32 and 33.

With the yoke structure and pressure rollers retracted from the drivecapstan l1, film such as 14 may be readily inserted or removed.

When it is desired to drive the film, it will be inserted and the lever38 simply swung from its dotted line position shown to its initialposition, the hook means 40 engaging about the bearing 41 at the upperend of the drive capstan shaft 12. This action simultaneously releasesthe yoke structure through the eccentric cam members 24 and 25permitting movement of the yoke structure towards the drive capstan. Theeccentric cam members 30 and 31 simultaneously engage the resilientsprings 32 and 33 thus urging the yoke structure and the pressurerollers 15 and 16 into engagement against the drive capstan 11 with thefilm 14 sandwiched therebetween. Because of the free floatingarrangement of the yoke structure and because of the stabilization ofthe upper end'of the drive capstan shaft 12 by the lever 38, thereaction force components on the upper and lower ends of the rollers atthe points they are mounted to the yoke will be substantially equal anduniform pressure will be applied to the film. Moreover, the use of thetwo rollers as illustrated causes a relatively large area of the film 14to be in frictional engagement with the surface of the capstan roller11. This large area surface engagement takes place over the entireinside area of the film between its engagement points by the rollers 15and 16 respectively. Thus a relatively large pinching force may beapplied to the film by the pressure rollers and yet the unit pressurecan be kept relatively small because of the large area distribution Asalready mentioned, the free floating" arrangement of the yoke assures anautomatic self alignment of the axes of the rollers with the axis of thedrivecapstan so that there is an even distribution of forces all alongthe contact portions of the rollers. Finally, it will be evident thatbecause of the particular actuating means in the form of the cam shaft26 and associated eccentrically mounted cam members a relatively compactarrangement can be realized. It should be understood that the particularshowing in the drawing is not in the same proportion as would be anactual embodiment in order that the component parts may be clearlyillustrated. In an actual embodiment, the axis of the cam shaft 26 wouldbe disposed considerably closer to the rollers 15 and 16 and the yokearms 17 and 18 and associated rearwardly extending portions 20 and 21would be considerably shorter.

In its broadest aspect, it would also be possible to utilize onecentered cam member rather'than. the cam members 30 and 31 on the shaft26, referred to in the appended claims as a first cam member since it isonly essential to the invention that the yoke be resilientlysymmetrically urged towards the drive capstan. The same is true of theadditional cam members 24 and 25 referred to in the appended claims as asecond cam member. By utilizing the second cam member or the pair asshown cooperating with the slots 22 and 23 in the yoke structure, thefeature of simultaneous retraction of the entire mechanism in responseto rotation of the lever for easy insertion or removal of film isrealized. It should also, of course, be understood that although theinvention has been described with respect to film the principles areclearly applicable to tape or any other type of strip media whichnormally is not provided with sprocket holes for driving purposes.

Finally, while the description and claims refer to a yoke structure forsupporting the pressure rollers, it is to be understood that suchterminology is meant to cover any equivalent type of mounting orsupporting frame for supporting the rollers.

The invention, accordingly, is not to be thought of as limited to theparticular embodiment shown and described for illustrative purposes.

What is claimed is:

l. A pressure roller means for engagement against a drive capstan formoving film passing therebetween comprising, in combination:

a. a yoke structure;

b. at least two pressure rollers rotatably mounted in said yokestructure with their axes of rotation parallel to each other, thespacing between said rollers being less than the diameter of saidcapstan;

c. frame means including guiding means permitting free limited movementof said yoke structure in all six degrees of freedom such that said yokestructure is free floating relative to said frame means;

d. resilient means; and

e. actuating means on said frame means cooperating with said resilientmeans to urge said pressure rollers against said capstan whereby thereaction force components transmitted to the supported end of saidpressure rollers in said yoke structure are substantially equal.

2. The subject matter of claim 1, in which said actuating means includescam means for engaging said resilient means.

3. The subject matter of claim 2 in which said cam means includes a camshaft mounted in said frame means for rotation about an axis generallyparallel to the axes of said pressure rollers; and a first cam member onsaid cam shaft for engaging said resilient means when said cam shaft isrotated from a first position to a second position.

4. The subject matter of claim 3, including a second cam member forengaging said yoke structure and urging the same away from said drivecapstan in response to rotation of said cam shaft from said secondposition back to said first position.

5. The subject matter of claim 4, in which said drive capstan is drivenfrom one end leaving the other end free; a bearing on said other end,said actuating means including a lever element secured at one end tosaid cam shaft and extending laterally therefrom, the other end of saidlever element terminating in a hook means for engaging said bearing onthe other free end of said drive. capstan when said cam shaft is rotatedto said second position to thereby stabilize said drive capstan whilesaid pressure rollers are engaging the same.

UNITED STATES PATENT OFFTCE CERTIFICATE 9F CORRETION Patent NO. 3 669331 D t June 13. 1972 I-n Q Walter Renold It is certified that errorappears inthe above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 4, line 44 Change "end" to --ends--.

Signed and sealed this 26th day of September 1972.

(SEAL) Attest;

v EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents ORM P0-1050 (10-69) USCOMM-DC 60376-F'69 U.S. GOVERNMENTPRINTING OFFICE: I969 0-366-334

1. A pressure roller means for engagement against a drive capstan formoving film passing therebetween comprising, in combination: a. a yokestructure; b. at least two pressure rollers rotatably mounted in saidyoke structure with their axes of rotation parallel to each other, thespacing between said rollers being less than the diameter of saidcapstan; c. frame means including guiding means permitting free limitedmovement of said yoke structure in all six degrees of freedom such thatsaid yoke structure is free floating relative to said frame means; d.resilient means; and e. actuating means on said frame means cooperatingwith said resilient means to urge said pressure rollers against saidcapstan whereby the reaction force components transmitted to thesupported end of said pressure rollers in said yoke structure aresubstantially equal.
 2. The subject matter of claim 1, in which saidactuating means includes cam means for engaging said resilient means. 3.The subject matter of claim 2 in which said cam means includes a camshaft mounted in said frame means for rotation about an axis generallyparallel to the axes of said pressure rollers; and a first cam member onsaid cam shaft for engaging said resilient means when said cam shaft isrotated from a first position to a second position.
 4. The subjectmatter of claim 3, including a second cam member for engaging said yokestructure and urging the same away from said drive capstan in responseto rotation of said cam shaft from said second position back to saidfirst position.
 5. The subject matter of claim 4, in which said drivecapstan is driven from one end leaving the other end free; a bearing onsaid other end, said actuating means including a lever element securedat one end to said cam shaft and extending laterally therefrom, theother end of said lever element terminating in a hook means for engagingsaid bearing on the other Free end of said drive capstan when said camshaft is rotated to said second position to thereby stabilize said drivecapstan while said pressure rollers are engaging the same.